Excessive weight gain during pregnancy, particularly in overweight and obese women, predisposes to adverse perinatal outcomes and has long term effects on maternal and neonatal health. With an inverse relationship between socioeconomic status and obesity, significant health disparities exist between obese and normal weight women. The Institute of Medicine (lOM) recently revised its gestational weight gain recommendations, targeted to pregravid body mass index (BMI), to minimize pregnancy complications. However, these recommendations are based on cross sectional observational studies and neither the ideal method to achieve weight gain goals nor whether perinatal outcome is optimized with active management of weight gain is known. We propose to investigate a behavioral incentive-based intervention to improve compliance with lOM weight gain recommendations during pregnancy in low-income overweight and obese women. We will evaluate if 1) gestational weight gain can be reliably targeted to the lOM recommendations and 2) active weight gain management during pregnancy improves perinatal outcomes. Two study groups will be compared in a prospective randomized trial; 1) those receiving standard obstetrical care and 2) those receiving behavioral weight management counseling plus financial incentives for achieving weight gain goals. The main outcome measure will be the percentage of women gaining within the lOM recommendations based on prepregnancy BMI. Secondary outcomes evaluated will include fetal growth and body composition changes, birth weight and the rate of cesarean delivery. We hypothesize that 1) the behavioral intervention with incentives will result in greater compliance to lOM guidelines for gestational weight gain than standard care and 2) targeting weight gain to the lOM guidelines will lead to a reduction in the rates of fetal macrosomia and cesarean delivery. Finally, cost effectiveness of treatment conditions will be examined. This intervention, if efficacious and cost-effective, has the potential to improve compliance with gestational weight gain guidelines, optimize perinatal outcomes, and reduce health disparities.